The invention relates to a two-chamber dispenser for a gas-pressurized or non-pressurized package, said dispenser comprising a rigid or semi-rigid one-piece can body with a shoulder forming a flanged opening and inserted therein a flexible inner pouch (herein after simply pouch) of a material which forms a barrier to diffusion, said pouch being for liquid, pasty or creamy contents.
There are various two-chamber dispensers for gas-pressurized and non-pressurized packages which permit separation of a propellant from the contents.
In the case of one two-chamber package a pressure-resistant can body contains a flexible, folded or semi-rigid pouch which can be deformed radially and/or axially. The pressure of the propellant between the pouch and the can body is so great that on opening the valve the liquid, pasty or creamy contents are expelled from the container. For environmental reasons the main propellant gases used today are nitrogen, air and liquid methane, which are fed or forced into the container through a sealable hole in the base of the can body.
By using a pump facility, which for physical reasons is particularly suitable for low viscosity fluids, the contents are sucked out of the pouch. There is no excess pressure in the space between the flexible pouch and the can body. The contents removed from the pouch cause the volume of the pouch to become smaller; the resultant negative pressure is constantly equalized.
Known versions of two-chamber dispensers for gas-pressurized and non-pressurized packages exhibit the following disadvantages:
The resistance to diffusion is not sufficient, either because the material used does not provide an adequate barrier, or because the connection of the pouch to the valve or pump facility is not sufficiently airtight.
The material necessary to provide a perfect barrier to diffusion e.g. in the form of an aluminum sleeve, is too thick. Under the action of radial compression the residual volume is large, which results in a loss of material i.e. contents. Axial compression is not possible here. Furthermore, under the action of radial deformation kinking or buckling can occur producing stresses that could lead to perforation (British Patent Document 2162901.)
The pouches are secured in a complicated manner e.g. in two-part can bodies. PA0 Known two-chamber dispensers are very expensive making the final product difficult to sell.
The object of the present invention is to develop a two-chamber dispenser of the kind discussed above which is diffusion-proof also in the region of transition to the valve or pump, even with critical products and this for several years, at the same time permitting manufacture at a favorable cost. Furthermore, the residual volume which is left in the pouch after emptying should be small. Finally, and this is of particular importance, the filling operation should save the introduction and attachment of the pouch to the can body.